Some conventional radio paging receivers have a function that a received message is displayed or notified only when a specific password is included in the message. For example, such a radio paging receiver is disclosed in Japanese patent application laid-open No.6-152499(1994) an titled "Radio Paging Receiver with Display".
This radio paging receiver is provided with a notification limiting means for notifying only when a predetermined specific password is included in the message. It is further provided with a time setting means which makes the notification limiting means effective at first predetermined time and makes the notification limiting means ineffective at a second predetermined time and a notifying means which notifies a notification-limited message at the second predetermined time.
In the conventional radio paging receiver, a password is previously stored in the radio paging receiver by the user, and, when a message is received during the notification control period using a password, letters included in the message are collated with the password stored in the radio paging receiver. When they are not identical with each other, the notifying operation is limited.
Meanwhile, a user may desire that the notifying operation is limited to conduct only for specific callers even when the notification control is conducted using the password. However, in the conventional radio paging receiver, such a further limitation operation is complicated and difficult to conduct.
On the other hand, the user of the radio paging receiver may change the password since the password can be freely set by the user. Unfortunately, when the message sender (caller) does not known the changed password, the message cannot be transmitted without delay.